Rob's Franken-Mods

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 12:34 pm

Rather than keep dotting my various design changes over different threads, I decided to get a little retrospective and backfill my build log, then document my changes for the community.

Here is my original setup
01 ShapeOko cutting cork-sm.jpg
Stock ShapeOko 2
01 ShapeOko cutting cork-sm.jpg (237.08 KiB) Viewed 4383 times
By this time (second cut after 'Hello World') I have already added my first 'mod' - a cardboard 'chip catcher' to minimise the amount of material, cork in this case, from covering everything around the machine!

Here is the first 'proper' modification I have made, creating a nylon mount for the generic spindle. I was not happy that the original needed to be packed out to remain vertical, so I fixed it.
05 Design and build mounts sm.jpg
First real upgrade
05 Design and build mounts sm.jpg (228.4 KiB) Viewed 4383 times
Here they are in position
08 Upgraded mounts in Nylon sm.jpg
Mounts in use
08 Upgraded mounts in Nylon sm.jpg (254.81 KiB) Viewed 4383 times
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 12:39 pm

Following on from these stages, I found that I was having a lot of trouble with two things - workholding and dust!

For the workholding problem, I decided to go down the insert nut route. It isn't perfect, but it does get the job done.
12 Workholding upgrade 2 sm.jpg
Workholding
12 Workholding upgrade 2 sm.jpg (247.55 KiB) Viewed 4381 times
Here it is in action with my first attempt at dust extraction:
13 Workholding in action sm.jpg
Workholding in action
13 Workholding in action sm.jpg (291.47 KiB) Viewed 4381 times
That method for dust extraction was OK, but having the vac tied to the machine was a pain if I needed to clear anything else up, so here is V2.0
14 Dust extraction upgrade sm.jpg
Dust extraction 2
14 Dust extraction upgrade sm.jpg (231.33 KiB) Viewed 4381 times
It's not pretty, but it does manage to grab a fair amount of the kicked up material. I will get on to a proper dust shoe design in due course, I think.
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 1:03 pm

So, having my work appropriately held, some of my dust extracted, my next problem was the number of times that my Gcode to Arduino process would fail in the middle of things. (My record is 26 times in a 3 hour stretch, in case you are wondering...)
I know why it is happening - electrical 'noise' in the system mainly due to my using the long leads on the stepper motors without shielding (bad idea!). I have a solution or two for that, but more on it later.
For now, I need to be able to reposition the machine at a point more accurately that I can by eye - hello limit/home switches and my new adventure in amateur electronics.

So, limit switches, how hard can it be? There's only 3-6 of them and there are connections on the board for them. Well, boy did I learn fast that they are not as simple as I expected.

I chose to go down the magnetic, or Hall Effect route as I thought they would be simple.

If there is one thing you need to know about limit switches, it is that they are very susceptible to electrical noise (which I have no problems with, of course), particularly at low voltages. If you can run them at 24v (apparently) there are fewer issues than running them at the 5v we get from the Arduino. Oh well.

Here is my first board for controlling them:
16a Limit switch circuit board.jpg
Limit switch circuit board V1
16a Limit switch circuit board.jpg (103.71 KiB) Viewed 4375 times
At this stage I had yet to find out about all the noise issues, but I was still playing with it in a test environment, not on the machine itself.

Version 2 had more filtering capability than V1 and also had some plugs and fancy coloured wires!
16b Limit switch board V2.0.jpg
Limit switch circuit board V2
16b Limit switch board V2.0.jpg (159.8 KiB) Viewed 4375 times
Just so that you can get a feel for them, here is a shot of the sensors themselves, they are 3 x 4 x 1.5mm at the business end!
16c Hall sensors.jpg
Hall sensors are tiny!
16c Hall sensors.jpg (162.75 KiB) Viewed 4375 times
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 1:14 pm

Having the circuit up and running it was time to concentrate on how to fix them the the machine. I decided on some (fairly) simple mounts that I could hot glue the sensors into and bolt into the makerslide channels.
16 Limit switch mounts deburred sm.jpg
Limit switch mounts
16 Limit switch mounts deburred sm.jpg (231.86 KiB) Viewed 4372 times
This worked OK to a point, but I wish I had glued them after routing the wires in some cases, particularly on the X-Axis.

Here is the X-Axis mounting:
16d Limit switch mounted.jpg
Limit switch X
16d Limit switch mounted.jpg (213.42 KiB) Viewed 4372 times
Here is the Y-Axis mounting:
16e Y Axis limits.jpg
Limit switch Y
16e Y Axis limits.jpg (192.31 KiB) Viewed 4372 times
I don't have a shot of the Z-Axis as it is tricky to get the angle right.

Well, they work fine as Home switches but the electrical noise in the system with the motors and spindle trips the limits too often, so I disabled the limit function. I will get back to that problem, but it is a bit further down my list yet.

Homing functionality, however, is a gift from the Interrupted Working Gods! It makes it so easy to restart a job from the same place again and again.

Next stage is to look at alignment and accuracy, now that I can keep a job going (after a fashion)
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 1:40 pm

So, on to measuring the accuracy of things.

I decided to perform the classic 'Square Diamond Circle' test to give me something to check against. There is a lot of information on the web about this, but it all leads back to an old article that doesn't help in interpreting the outcome, so I had to draw my own conclusions about what the results meant. (Along with help from the forum team)

I drew out my shape and programmed up the cutting:
17a Accuracy testing.jpg
Accuracy testing
17a Accuracy testing.jpg (226.91 KiB) Viewed 4372 times
Here is the completed test piece, cut from MDF
17b Accuracy SDC.jpg
Square Diamond Circle
17b Accuracy SDC.jpg (218.45 KiB) Viewed 4372 times
From measuring it I found that there were some slight inconsistencies in my directions, but overall I was accurate to 0.25mm so I was pretty happy with that.
(More information here)

After that I decided to flatten the wasteboard to remove the slight skew I had to it - maybe the MDF didn't appreciate it's transatlantic trip...
Now I have a lovely flat staging area for clamping stuff onto.
17c Flattening.jpg
Flattening the wasteboard
17c Flattening.jpg (230.03 KiB) Viewed 4372 times
I also did spend some time measuring and messing around with the GRBL settings to fine tune my directional movements, but I will need to revisit them again soon and will update on that when I do.
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 3:07 pm

Next up is the ongoing saga of my upgraded spindle.

I bought a Chinese 800w spindle and inverter control unit from eBay. Mode info here.
It seems to work as anticipated but is very heavy, so I need to think about upgrading the Z-Axis to handle it.

There are three aspects to this part of my upgrades:
  • 1. Spindle mounts (for the 3rd time!)
  • 2. More powerful Z-Axis motor
  • 3. Lead screw upgrade
I had imagined that it would be a simple case of cutting some new spindle brackets, slap in the new spindle and off we go. Oh dear, not really.

I know that I am going to need to upgrade the Z-Axis motor, firstly because the NEMA17 gets so hot so fast with the stock spindle and secondly because the new spindle is such a lump.
To that end, I redesigned the top end of the Z-Axis to mount a NEMA23 without it protruding any further forwards than the original NEMA17. Details here.

In order to mount my new spindle, given it's cylindrical nature, I had to push it out from the Z-Axis even further than I thought, almost 25mm. Having decided that this was the case, I went ahead and started cutting some new mounts for it from some - along with a new idea for my vacuum mount.

Part way through this process, I managed to break the collet lock on my generic spindle. I knew it wasn't very robust, but I thought it might last longer. As I had a Dremel kicking around, I thought I would drop it into the mounts and off I go - wrong!

I had to hack up the generic spindle mounts in order to get the Dremel to mount and even then it was not really vertical. Darn! (and other naughty words)

At this stage I really didn't have much alternative than to plough on with the job and hope that it will be close enough. The mounts turned out pretty well, but the nice tolerance I had on my offset from the Z-Axis was shot and I had to add some spacers and 'modify' the top of my spindle with a belt sander to provide clearance. Ho-Hum.

The mounts don't look to bad considering the process. Here they are:
32 New Spindle Mounts.jpg
65mm Spindle mounts
32 New Spindle Mounts.jpg (159.04 KiB) Viewed 4364 times
Once I had them mounted (which was fun as I designed them to be attached from behind) I found that there was a large amount of deflection due to the offset weight of the new spindle. This spindle is so heavy (2.4kg - 5.2lbs!) that I really need to think about how to minimise the offset of the spindle from the gantry. So, back to the design scrapyard.

The best Idea I had for minimising the amount of distance between the mounting plate and the spindle was to redesign the top end of the Z-Axis again. The idea is to swing the Z-Motor upside down and push it back so that it sits over the gantry, then connect the motor to the Z-Axis with two GT2 pulleys and a belt. It should help on two counts, in theory.
  • 1. It improves the weight distribution by shifting the overall centre of gravity back towards the gantry
  • 2. It minimises the amount of 'stick out' at the top to just the amount needed to house the top bearing for the axis
The only down side that I can see is that it may need a lower bearing in order to counter the tension in the belt. On the positive side, it could be mounted easily so that the entire spindle/motor combination can be removed by taking out two screws... I am beginning to like that concept.

So, in order to sort out my stiffness problems (har-har) I decided to use some spare 20x20 extrusions left over when I extended the base.

(Oh yeah, I reinforced and extended the base of the machine with 20x20 extrusions).
33 Base extension.jpg
Base extension
33 Base extension.jpg (199.75 KiB) Viewed 4364 times
So my design for the X-Axis strengthening is described here, as work in progress.

Here is a drawing of what I actually constructed:
24 X-Axis upgrade.jpg
X-Axis upgrade
24 X-Axis upgrade.jpg (203.25 KiB) Viewed 4364 times
It was a fun exercise for me, using some of the manual machines I have access to.
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 3:14 pm

Here are some shots of the W.I.P. of the X-Axis upgrade.

First I clamped the sections together - not very simple, I'll tell you! I managed to put a couple of nasty dings in the MakerSlide :(
Then I attacked them with my drill...
24 Drilling X-Axis Links.jpg
Drilling
24 Drilling X-Axis Links.jpg (292.78 KiB) Viewed 4363 times
Bolted them together
25 Bolt fixings on X-Axis.jpg
Bolting
25 Bolt fixings on X-Axis.jpg (234 KiB) Viewed 4363 times
Then used my milling machine to square up the ends (I love my milling machine, but she's a big old lump)
26 Milling the ends flush.jpg
Milling the ends square
26 Milling the ends flush.jpg (250.23 KiB) Viewed 4363 times
I did end up swinging the assembly through 90degrees and taking 0.1mm off both ends with a nice slow finish cut, after the cut you see there with that corn-cob cutter!
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 3:20 pm

Then I moved on to the gantry spacers. I turned these on the lathe and managed to get them all to within 0.002' of each other, which I was pretty pleased about.
I designed them to be fitted easily with button head cap screws and washers.
27 Fitting new spacers.jpg
Fitting spacers
27 Fitting new spacers.jpg (358.33 KiB) Viewed 4363 times
Here you can see them all in place and the revised spacing between the plates.
28 New Carriage spacers in situ.jpg
New spacers
28 New Carriage spacers in situ.jpg (256.87 KiB) Viewed 4363 times
Finally you can see a test assembly of the gantry on the x-Axis MakerSlide assembly which was a lovely smooth fit.
29 X-Axis sections bolted together.jpg
Test fitting Gantry
29 X-Axis sections bolted together.jpg (132.68 KiB) Viewed 4363 times
The last pic was before I skimmed the end, so you can see the marks I was using to ensure that I could realign everything each time I dropped it!
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 3:32 pm

The next part was a bit of lateral thinking for me as I wanted a way to route my limit switch and motor cables across the gantry without hanging them off the outside. Originally I had done this by running them in between the MakerSlide pieces, but now I no longer have a gap to use. I thought about it for a while until I realised that there are two lovely clear channels through the middle of every piece of MakerSlide, all I had to do was to provide access to them through the carriage plates.

I have designed my (new) motor cabling with plug/socket arrangements close to each motor and I have kept these small, which means that I am able to run the cables through the holes in the MakerSlide as I had hoped. All that remained was to chop lumps out of the carriage plates...

I cut two slots into the plates, aligned with the middle of the channels, for the cables. I also enlarged one of the unused mounting holes so that I can get my limit switch cables through it. Finally, I added another hole above another unused one for mounting a bracket to hold my drag chains, when I get up and running so that I can cut them out!
31 Carriage plate mods.jpg
Carriage plate mods
31 Carriage plate mods.jpg (227.43 KiB) Viewed 4361 times
Here you can see the reassembled gantry
34 X carriage in place.jpg
X Carriage
34 X carriage in place.jpg (215.08 KiB) Viewed 4361 times
With a close up of the access holes to the inner channel of the MakerSlide
35 Carriage up close.jpg
Close up
35 Carriage up close.jpg (102.79 KiB) Viewed 4361 times
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

RobCee
Posts: 587
Joined: Wed Jan 08, 2014 11:33 am
Location: Birmingham, UK

Re: Rob's Franken-Mods

Post by RobCee » Fri Mar 14, 2014 3:43 pm

The other thing I have been working on is an enclosure for hooking everything up to. The driving force behind this is wanting an emergency stop, but it does tend to snowball when you start on it.

Here are some of the innards of my (one day) enclosure
36 Enclosure innerds.jpg
Enclosure bits
36 Enclosure innerds.jpg (266.37 KiB) Viewed 4356 times
ShapeOko2 #3400 - Chinese 800W AC Spindle - Stiffened X-Axis - TR10 Z-Axis - Inverted Z Motor - Hall Effect Limits - Drag Chains & Custom Brackets

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